Linux – how to add static route to specific host

I'm currently using "strongSwan" ipsec VPN client on linux.

I can connect to my VPN server, default route automatically set to 10.10.10.1.
And I can access my local network by ip route add 192.168.7.0/24 dev ens33

ip route list output:

default via 192.168.7.1 dev ens33 proto static src 10.10.10.1
172.17.0.0/16 dev docker0 scope link
192.168.7.0/24 dev ens33 scope link

Everything works well !

BUT!

Now I need to connect to another server from "my real IP", not VPN server.

(the server ip is 1.2.3.4 eg.)

I can ping 1.2.3.4 with 300ms lag, but can't connect because my IP was wrong.
Without VPN connected, ping will be 2~6ms.

Question: How to specify route to 1.2.3.4, when default route is set to VPN

I have tried ip route add 1.2.3.4 dev ens33
But failed with "Destination Host Unreachable"